One aspect of the present invention relates to methods for splitting objects made of brittle materials and, in particular, methods for splitting semiconductor wafers made of brittle materials.
Known in the art are methods for cutting and splitting objects made of brittle materials such as glass, sapphire, quartz, silicon, germanium, ceramic, and many others. An important industrial application of brittle material cutting is semiconductor manufacturing where one semiconductor wafer is diced into many separate, smaller pieces.
Brittle material cutting and splitting methods range from conventional sawing to splitting with mechanical force or with a scribing/abrasion tool, to thermal splitting with or without a thermal shock process, laser ablation, or a combination of any of the above. US 2004/0251290 A1, provides, in the introduction section thereof, a summary of some of the well-known conventional brittle material splitting methods.
Among the many limitations of the conventional methods are inefficiency and low quality of edges obtained with these methods. To improve these aspects, EP 0 633 867 B1 discloses a method for splitting bodies of non-metallic brittle material, such as glass, by scoring a certain point of the material to a certain depth followed by splitting it with some splitting method. The scoring, however, inevitably causes an “initial damage” to the material. Although claimed to provide for increasing splitting speed and improving edge quality, this method may nevertheless require an “initial damage” to be made to the object of brittle material at the start of each splitting which may cause intolerable problems. For example, in certain applications, such as semiconductor wafer dicing, many such “initial damages” are required due to the requirement of cutting the wafer in both X and Y directions. This is very time consuming and for small dies not practicable.
In addition due to the very “initial damage,” the quality of the edge(s) of the separate wafer pieces or devices finally produced would suffer; besides, low-quality edge(s) would in turn degrade the pieces or devices in terms of mechanical properties, such as the robustness and electrical properties, such as the electrical leakage current of the device.
Thus, a method for splitting objects of brittle materials that is fast, produces high quality edges for the end pieces, and causes little or no mechanical and electrical property loss to the end pieces would be a useful improvement.